Picture reproducing device for television



Nov. 22, 1932. L. TSCHGRNER 1,883,893

PICTURE REPRODUCING DEVICE FOR TELEVISION I 7 Filed Feb. 26. 1931 l I 1 1 I Patented Nov. 22, 1932 UNITED STATES PATENT-OFFICE,

LUDWIG rrsoHoRNER, on VIENNA, AUSTRIA rrorunn nnrnonoenvci DEVICE non rnnnvrsroiv Application filed February 26,1931, Serial no. 518,511, an in Austria November 16, 1929.

The invention relates to a picturereproduc-' pass through when the dark screen units cover' one another and stopping the passage of the light when a displacement'takes place to the extent of the width of a screen unit.

The invention makes it possible to impart to the reproduced picture a degree of brightness limited only by the intensity of the i1 luminant available, since there is no restric tn as to thechoice of an illuminant. Furthermore, thecontrol of the screen requires little mechanical power and is extraordinarily reliable' I 7 I When an ordinary screen of the dot, line or checkerboard type-is employed, the neces sity arises to render eachunit or element displaceable independently of all'othersf As.

" the'number of units amounts to several thousands, the apparatus becomes too'complex for the reason that veach element requires a sp e'cial electromagnet or another system of motion, the number of which renders the area of 139 image expensive and-complicated. More-- over, the driving systems cover the path of the light and produce troublesome dark spots on the reproduced picture.

Accordin the passage of the strip and the strips ar-- ranged vertically thereto are moved sep arately during the impulse for each unit. V The displacement of a single strip will not brighten the picture, but brightening willbe e'fe fected if a counterstrip disposed'vertically to the'firstistrip is displaced. At the crossing of the two screenstrips the'picture will r reb'e brightened to the extent of to the invention, these draw backs are eliminated by the employment of unit only during the displa'cement of the second strip. The advantage connected with this arrangement is that each single strip may. be moved by a mechanism located outside the image area and that thenumberfof these driving mechanisms may be reduced to a fraction of that normally required. Instead of a cross screen,-"line screens may be used having lines that are inclined"45 relative to the direction of motion of the screen, or jaggedscreens may be employed. In'either case, however, the lines of one of the screen 1 strips must be-twice as broad as those of the other to prevent brightening at the displace ment of only one strip.-

' By way of example, one form of the invention is illustrated "in the accompanying drawing, injwhich Figure 1 is a top View of the image reproducing area with two screen. strip systems having the form of a'ruler; and Fig. 2, a view of thestrips on an en-I larged scale. p

'The area of imageis divided in two coordinate directions into strips. The strips 1 are, for example, displaceable in horizontal .direction andthe strips 2, vertically disposed to the strips 1, in vertical direction. The strips are displaced by means of the electr1omagnets 3 and 4 which draw the strips" against the action of the springs'5 which re-' 801 turn the strips into their initial position after magnetic induction ceases. The image point excitation takes place, for instance, from top to bottom along a strip 2 and always passes over the adjacent strips2 also. During the 851 passage of the strip 2, the-latter remain con tinually in its drawn down position while, ac-' cording to the speed of the optical excitation passing over the strip 2, the strips 1 are f moved successively transversely over the 9 strips 2. p I

In their initial position the screens of the strips 1 and2 are'arranged relative to one another in such a way that no transparent places are produced and: the lines ofoner screen cover the transparentlines ofthe counterscreen." The sole displacement of the, v strip .2 does not result in the brighteningofj the image by means of the constant pow er' ful illuminant, such as an arc lamp, since the; '99

displacement of the longitudinal screen strips constitutes merely a displacement within themselves. On the other hand, the motion of each strip 1 will produce a brightening of the area common to both screens, i. e., the area of crossing which may be represented by a single screen unit or a group formed thereof; the latter case is preferable, since the brightening of the entire area may be effected by a smaller motion of the strips. In Fig. 2, the upper right-hand field where the strips 1 x 2 cross is brightened while the fields 1 x 2, 1 x 2 and 1 x2" are dark.

The construction .of strips affords the added advantage that current of any intensity may be used for moving the screen row covering a row. of units lying in one line and being displaced first, as; the proper modulation of the picture is effected by the strips disposed transversely thereto. Image current is thereforerequired merely for. actuating these lata ter strips, while. current of any originjmay beused for actuating the, first'one. It is probably the most practical arrangement to construct the screen rows like rulers and to. arrange them vertically to one another, though the rulers may, be inclined relative to a one another also. The image reproducing area may possess the s ze of the original or act asdiapositive through whichan illumi- V The screen devicemay be employed also as light relayin connection with a picture reducing device, such as a Wipkov disc, a mirror Wheel or the like. For this purpose two superimposed screen strips of low weight and made, for example, of celluloid are moved relative to one another. For example, one of the two strips is moved byan electromagnet, the excitation of which is controlled 'at to intensity by the subsequently arriving. intensified image currents. By providing a large number of screen lines it becomes possible to obtain a large free passage section for the pencil of rays of the constant illuminant by means .of a slight displacement of the screen strips. In the order of the picture units worked by the transmit ter, the screen inthe receiver is shifted more or less, proportionally to the luminous intensity of the analogous image points in the sender, so as to letthrough more or less light and to control in thismanner the current of light sent through the screen by a powerful constantilluminant in the proper order and intensity. In order to reduce still more the strips to their initial position, and an illuminant, the light of the. said illuminant passing through the said strips when the dark screen units are covered and 1 being stopped when the said screen strips are displacedfor the width of a unit. 2. In adevice accordingto' claim 1 a picture reproducing area subdivided into elements arranged analogous to the Worked points of the transmitted image, each of the said elements consisting of; a pair of screen ps l I 3'. In a device according to claim 1, apie -i ture reproducing. area consisting of two rows of screen strips in the form of rulers and arranged vertically to one another, a cross screen carried by the said screen rulers, and means for producing and guiding optical excitations successively by rows or strips,

one of the said screen rulers being permanently displaced during the excitationof a row and the notion of all rulers arrangedtransversely to the permanently displaced; one taking place successively according to the excitationof each individual unit.

4:. In a device according to claim; 1, a picture reproducing area consisting of rows of screen strips in the form-of rulers and, adapted'to be displaced by rows in accordance with optical motion impulses, theruler. through which the impulse has passedbeing. moved according to the unit excitations and the motion of each crosswise ..r-uler taking place successively according to the excita tion of each unit. V i

5, In a device according to claim 1, a pic-r ture reproducting area consisting of rows of movable screen stripsi'n the form of rulers, me'ansfor exciting the .saidrows, one of the said rows remaining displaced forthe length of theexcitationofa row, lines in the said screens inclinedrelative to the direction of displacement ofrthe.rulers,thelines of one group of rulers exceedingi'n width those of the other to the extent'of their mutual'dis placement in order to prevent the'produc tion of screen portions 'adaptedftoletlight pass through during the displacement ofthe ios said ruler remaining displaced forthe lengtlrdark lines, so that light conducting slits are produced, and so that the device is transparent when the strips are so displaced as to cause their lines to register, and is opaque when'the strips are so displaced as to cause the dark lines of one screen strip to register with the light gaps of the other screen strip. In testimony whereof I afiix my signature.

LUDWIG TsoHoRNER. 

